Process for production of potassium hydroxide composition



Patented Aug. 23, 1949 rRocEss FOR PRODUC nvnaoxmn o TION OF PQTASSIUMOMPOSITION Glen H. Morey and Everet F. Smith, Terre Haute,

Ind., assignors to Commercial Haute, Ind., a corporation of poration,Ierre Maryland N Drawing. Application Solvents Cor- June 11, 1945,

Serial No. 598,919

6 Claims.

Our invention relates to a novel process for obtaining potassiumhydroxide in a finely-divided and highly-active state. Moreparticularly, it relates to such finely-divided and highly-activepotassium hydroxide in the form of a suspension in a mixture of a liquidhydrocarbon and a small proportion of a monohydric alcohol containingfrom three to ten carbon atoms, and to a method for preparing suchsuspensions by heating solid potassium hydroxide or aqueous solutionsthereof in the aforesaid hydrocarbon and alcohol, as describedhereinafter.

For carrying out various chemical processes, it is often desirable toutilize potassium hydroxide in a finely-divided state, suspended in acarrying medium. This is particularly true, for example, in thereactions involving the absorption of l-alkynes such as acetylene, inwhich a very large surface area of the potassium hydroxide must bepresent to absorb the acetylene and to convert'it into a form suitablefor subsequent reaction, with carbonyl compounds to form acetylenicalcohols.

Ordinary mechanical methods for obtaining the potassium hydroxide in thefinely divided and highly-active state necessary for this and otherpurposes have presented many difiiculties. Mechanical grinding of thesolid potassium hydroxide has been difiicult and not as efiective asdesired because the solid potassium hydroxide presents a waxy effect tothe grinder and resists comminution. This results in a product that istoo coarse for easy suspension in the carrying liquid, and too coarsefor most efiective use inthe processes referred to.

We have now found that solid potassium hydroxide can be heated to itsfusion temperature with a .water-immiscible-liquid of the typehereinafterdescribed and subsequently cooled with agitation below itsmelting point to form a slurry of finely-divided solid particles ofhighly reactive potassium hydroxide in the Water-immiscible liquid.Commercial potassium hydroxide U.- S. P. pellets containing 10-13% watermay be thus fused at atemperature around 100 C., and hence, a relativelylow-boiling hydrocarbon can be used. With other grades containing lowerpercentages of water, it is necessary to use higherboiling hydrocarbons,or to operate the reactor under pressure, in order to effect fusion.

We have also found that when a water-imniscible liquid of the typehereinafter described s added to an aqueous solution of potassiumhylroxide and the mixture distilled with accomianying vigorousagitation, with removal of the vater from the distillate and return ofthe waterimmiscible liquid to the distillation vessel, the free water,as hereinafter defined, can be substantially completely separated fromthe mixture, leaving a two-phase liquid residue which, when agitated andcooled, is converted into a suspension of finely-divided, solidparticles of highly reactive potassium hydroxide in the water-immiscibleliquid.

The removal of all of the distillable water, as. mentioned above, doesnot leave the still residue.

On the contrary, it may below one mole of water per mole of potassiumhydroxide, depending on the boiling point and relative concentration ofthe liquid used for carrying out the dehydration. The water, however,does not behave like free water; it is apparently sium hydroxide, anddoes not interfere with the activity of the residual anhydrous potassiumhycompletely anhydrous. contain up to slightly dro-xide. In thisconnection, the expression free.

water herein referred to, is to be construed as meaning only that waterwhich may be removed from the above-mentioned mixtures by distillationwith a mixture of a liquid hydrocarbon and a small proportion of amonohydric alcohol containing from three to ten carbon atoms.

The complete separation of water from the potassium hydroxide solutionis not essential for the preparation of a solid, finely-divided, activeproduct utilizable for the processes described. In fact, the preparationof a strictly anhydrous potassium hydroxide would not be practical,since it has a melting point of about 360 be difiicult or impossible tomaintain in fluid condition at the boiling temperatures of'many of thewater-immiscible liquids of our invention. The product as it commonlyappears in the socalled "dry solid state as a commercial material issufficiently dehydrated for our purposes. This form of potassiumhydroxide fortunately can be maintained in a liquid condition attemperatures considerably below the melting point of anhydrous potassiumhydroxide, so that it remains in fluid form at the boiling temperaturesof the various water-immiscible liquids of our invention; and in suchfluid condition the potassium hydroxide mayv readily be comminuted bythe vigorous agitation and cooling employed in our process, and therebyfinely dispersed in the carrying liquids described. Other liquids whichwe may use have somewhat higher boiling temperatures, but as a matter ofconvenience the majority of the liquids most adaptable to our processeswill have boiling points ranging from about to 250 or 300 0., con- 7combined with the potas- 0., and would quantities of and duringsiderably below the melting point of the anhydrous potassium hydroxide.

The particular advantages of the potassium hydroxide composition of thepresent invention will be recognized when it is recalled that wits priorexisting methods involving the utilization of anhydrous potassiumhydroxide, workers were confronted with the problem of recovering largethat material from aqueous mixtures, dehydrating the potassiumhydroxide, and then pulverizing it for re-use in the succeeding batch.It will be obvious that this requirement renders such practicesubstantially useless from an industrial point of view, since it is noteconomically feasible to recover large quantities of potassium hydroxidethereof in an anhydrous condition and then to grind the materials to afinely-divided powder suitable for re-use.

In accordance with ourinvention, we utilize hydrous potassium hydroxide,either as the solid base, preferably the U. S. P. grade which containsapproximately 12.5 per cent by weight of water, or aqueous potassiumhydroxide of substantially any concentration, although of course, themore concentrated the solution, the more quickly will the waterseparation be effected.

The potassium hydroxide or solution thereof, as the case maybe, is'mixedwith the appropriate'water-immiscible liquid and alcohol asde scribed.hereinafter'and is subjected to distillation in such a manner that the.free water is removed as a separate layer fromthe distillate, and,discarded, while thewater-irnmiscible liquid and alcohol arecontinuously returned to the distillation vessel. Distillation iscontinued until no. more water distills over. The still contents thenexist in the form of two liquid phases, one phase comprising thewater-immiscible liquid and alcohol, the other the fluid potassium hy--droxide. After the distillation is complete, the contents of thedistillation vessel are allowed to cool,usual1y down to room temperatureto permit solidification of the potassium hydroxide,

this cooling stage the vigorous agitation is continued; The agitationmay be effectedby any of the convenient known methods, but theturbulence should be of a magnitude sufiicient to effect fineprecipitation and thorough dispersion of the finely-dividedparticles.Potassium hydroxide, treatedin this manner, presents a greater activesurface than that produced by mechanical means, or by other processesusing different types of dehydrating liquids; hence, a' given weight ofsuch potassium hydroxidewill produce a greater weightof product in-thereactions for which it is adapted.

from aqueous mixtures of suitable hydrocarbons are toluene, xylene,aliphatic naphthas, tetrahydronaphthalene, and decahydronapthalene.

As specific examples of the alcohols suitable for use in our process maybe mentioned butanol, Z-butanol, -t-butyl alcohol, isobutyl alcohol,methallyl alcohol, isoamyl alcohol, capryl alcohol, ethylene glycolmonoethyl ether, phenol, cyclohexanol, and tetrahydrofurfuryl alcohol.

The proportion of alcohol to hydrocarbon may vary considerably. However,it has been our general observation that satisfactory results areconsistently obtained when up to about 35 per cent of the alcohol, basedon the total volume We --obtain our improved finely-divided andhighly-active potassium hydroxide by the use of mixtures ofwater-immiscible liquid hydrocarbons which' do not react irreversiblywith potassium hydroxide, and a small proportion of a monohydricalcoholcontaining from three to ten carbon-atoms. Such mixtures of hydrocarbonsand alcohols, it has been observed, have theproperty of activatingpotassium hydroxide for :many reactions, the degree of activation being.greatly enhanced by. our processing techniques. Liquid hydrocarbonswhich are to be utilized under atmospheric pressure shouldpreferably-possess aboiling point of at least about- 100 C.Lower-boiling hydrocarbons can be used,

but require .the application of super-atmospheric pressures in order toproduce the desired liquid layer of potassium hydroxide. Specificexamples of the reaction menstruum, is utilized.

The finely-divided suspended particles of potassium hydroxide preparedby the use of mixtures of liquid hydrocarbons and a small proportion ofmonohydric alcohols containing from three to ten carbon atoms appear todiffer decidedly both in size-and physical-structure from the particlesof potassium hydroxide obtained by priorprooesses. They are, forexample, somewhat rnore finely-divided than those formed in thehydrocarbons without the presence -ofthe alcohol, and of a iiuffy orleafy characterrather than of a'sandy character'siuch as isobtained inhydrocarbons alone. The physical characteristics of our potassiumhydroxide particles-produce a more-enduring type of suspension; and whenthe particles do settle somewhat, they settle loosely withoutcompacting, andcanreadily be resuspended With gentle'stirring.

When a-mixtureof ahydrocarbon and'an alcoholof-the above type is used-topreparea-finelydivided suspension of potassium hydroxide in accordancewith our procedure, a grade of potassium hydroxide isobtained which whenused in the condensationof suitable l-alkynes with carbonyl compounds,ordinarily gives both a higher conversion to acetylenic alcohols andahigher output of acetylenic alcohols per unit volume of thereactionmenstruum.

Although-the potassium hydroxide mixtures of the present inventionabsorb l-alkynes readily,

substantially all of the latterare released if the solution is thenheated; and the residue can again be used for further absorption. Thesepotassium hydroxide mixtures will, therefore, be found usefulfor theremoval of .l-alkynes of the-abovementioned class from various gasmixtures.

Our invention may be further illustrated by the examples which follow:

Example I A mixture consisting of 558 ml..of xylene, 42

ml. ("approximately '7 percent) of'butanol, and 187 g. of potassiumhydroxide U. S. P. pellets containing 13% of water, was refluxed forfifteen minutes, during which time two liquid layers were formed. Themixture was then cooled to -10 C.

with .agitation' The resulting composition consisted of .a suspension offinely-divided solid particles. of potassium hydroxide in xylene andbutanol.

Example II A mixture consisting of 558 ml. of aliphatic suspension offinely-divided solid particles of .P. pellets containing 13% 0fpotassium hydroxide in aliphatic naphtha and butanol.- i

Example III A mixture. consisting of 55.8 ml. of tetrahydronaphthalene,42 ml. of butanol, and 187 g. of potassium hydroxide U. S. P. pelletscontaining 13% of water, was refluxed for fifteen minutes, during whichtime two liquid layers were formed. The mixture was then cooled toC..with agi- It will beobvious to those skilled in the art that'otherwater-immiscible hydrocarbons and alcohols of the character described,in addition to those specifically enumerated herein, may be utilizedincarrying-out our invention, and that the above examples are merelyillustrative of our invention and in no way limit the scope thereof. Onthe contrary, 'it is intended that the present inventionshall cover, bythe terminology of the tation. The resulting composition consisted of 10g? gz g patentable nova suspension'of finely-divided solid particles ofe -Y 1c i i eljen m potassium hydroxide in tetrahydronaphthalene Thisapphcgtlon 1S cpntmuatlon'lmpart of and butanol our U. S. Serial No.511,838, filed November 26,

1943, now abandoned.

Example IV 15 Having described our invention, what we claim A mixture of558 ml. of xylene and 42 ml. of is! butanol were added to a solutionconsisting of 1. A process o p od g a highly-active 187 g. of potassiumhydroxide dissolved in 374 ml. pension f solid p si m hyd x e w h c ofwater. The resulting two-phase mixture was p s miXing a ydrous potassiumhydroxide heated to reflux temperature, and the water re- With a liquidhydrocarbon which boils within the moved therefrom in the form of anazeotropic range of about 100 to 300 C. and which does not mixture withthe xylene and butanol. The latter, substantially react irreversiblywith the potassium after separation from the water, were returned y o ad f a fl to 35 p cent of a to the still kettle. Throughout the heatingary nohy ric lc h l co n fr period, and also during the subsequentcooling, three to ten carbon atoms, heating the mixture the mixture wasstirred vigorously. The resultabove the melting point of the hydrouspotassium ing composition consisted of a suspension of hydroxide anddistilling off any water which may finely-divided, highly-activepotassium hydroxide be present in excess of about one mol of water inxylene and butanol. moi of potassium hydroxide, then cooling the Asurprising feature of our invention is the disresulting mixture tosolidify the potassium hycovery that potassium hydroxide prepared inaccordance with our invention using a mixture of hydrocarbons andalcohols is substantially more reactive than when prepared withhydrocarbons alone. This is illustrated by the data shown in thefollowing table, taken from experiments in which potassium hydroxideslurries were first saturated with acetylene and subsequently reactedwith acetone to form 2-methyl-3-butyne- 2-ol. bon used; column 2, themonohydric alcohol; column 3, the conversion to acetylenic alcohol; andcolumn 4, the menstruum output. In each case the potassium hydroxide wasprepared as de- Column 1 shows the particular hydrocari,

droxide while vigorously agitating to produce a finely-divided,highly-active suspension of potassium hydroxide.

2. The process of claim 1 wherein said primary monohydric alcohol isbutanol.

3. The process of claim 1 wherein said liquid hydrocarbon is xylene.

4. The process of claim 1 wherein said liquid hydrocarbon is aliphaticnaphtha.

5. The process of claim 1 wherein said liquid hydrocarbon istetrahydronaphthalene.

6. A process for producing a highly-active suspension of solid potassiumhydroxide which comprises mixing a hydrous potassium hydroxide scribed iExample with a liquid hydrocarbon which has a boiling Table Cfogvegsion0 cc one Hydrocarbon Alcohol to 2-Metllylglamtmum utput, g./]. 01, PerCent None 1.8 0.5 l-PropanoL- 80 24.9 Bu 1.101.. 92 66.5 -Butanol 78 45.3 t-Butyl. 64 15.0 Isobuty 43 43. 5 Methallyl 80 43. 5 Isoamyl O 67.3mttifir i i r" 8 g yco m 110- ethyl ether. 7 62 31.8 73 33. 5 Do 83 32.4N aphtha (aliphatic 84 40. 8 Tetrahydronaphthale 78 0. 6Decahydronaphthalene 56 33. 4

point within the range of about 100 to 300 C. and which does notsubstantially react irreversibly with the potassium hydroxide, and fromabout '7 to 35 per cent of a primary monohydric alcohol containing fromthree to 10 carbon atoms in the molecule, distilling the mixture toremove water in the form of the azeotrope with said liquid hydrocarbon,and said primary monohydric,

alcohol, removing the water from the distillate and returning saidhydrocarbon and said alco- 1101 to" the mix-tore, eontinuing medistillation 7 REFERENCES 01mm) untilmhe Water in mixture reduced to anThe following references are of recordzin'flle amount not substantlallyexceedmg one mol per me of this patent mol of potassium hydroxide, thedistillationbemg conducted'at a temperature sufiiciently high 5 STATES'PATENTS to cause at least partial fusion oithe potassium Number Name 7Date hydroxide, cooling the mixture while vigorously 118355271 I Burkeat alt v31931 agitating the same to solidify he potassium h 2,o 9,46,3Bacon och ,29, 1935 droxide and to produce a finely-divided, highly- 233 557 m t 1 7. 1942 active pension of'the same. 2,326,099 vKokatnur et.a1. Aug. 23,1943 GLEN H. MGREY. 2,367,273 Hall et a1. Jan. 16,, 1945EVERET F, SMITH. 2,385,547 Smith Sep1L25, 1945

